Fiberglass Quantity question for you glassers?

[john]

I want to coat my next tear in fiberglass rather than aluminum. I have two questions.

First...Is the cloth really needed? I have noticed it is sometimes not used.


Second...I am covering around 25 sq yards. How much epoxy will I need? I am clueless on this question.

[Terran]

If your doing fiberglass, then yes, the fiberglass cloth is needed, since, you know, that's what makes it fiberglass. However, It's alot of work doing actual fiberglass, if you were going to go that route, you'd be better off making the whole shell out of fiberglass and setting wood blocks to it for the interior trim.

[john]

Sorry. I need to learn terminology here. Thanks.

Should I glass (seal with epoxy) or fiberglass?

In each case my real question is how much epoxy might be needed to cover 25 yards?

This info would help me when ordering from RAKA.

[doug hodder]

I've done 4 tears using epoxy as the coating prior to clear coating or painting it, without any glass cloth. My side walls are solid ply however. I'm not sure on the use of the Raka system, but using the West product...I didn't use 1 full gallon of material in my construction or top coating on any 1 tear. Doug

[Juneaudave]

I agree with Doug...and if you are going to glass...go ahead and get the three gallon kit. I used the RAKA 60 " wide 4 oz glass over the top and just coated the sides with epoxy w/o glass to build up a surface.

[TomW]

I agree, get the three gallon kit. I used the thin epoxy from U.S. Composites and had great results.

I used 4oz 4" wide cloth on all of my seams, the build up is four coats over all of the tear. 5 x 10 Generic Benroy. I used about 2.25 gallons total mix.

My next project will have 1/4" sandwich walls with insulation and fiberglass over the entire surface.

I enjoyed working with the glass and epoxy. I tried several test joints/surfaces with the glass and fiberglass resin (Bondo brand), sets real fast and the smell is terrible. I did not like working with the extreme chemicals so I went with the epoxy in the end.

When you start, lay everything out where you can get to it, you do not want to be hunting something after you have mixed your resin.

[john]

Thanks...Off to buy.


One last question...

I like the way hardboard rounds curves but I am unsure if it will make a good base for the epoxy or not. Your thoughts?

[wannabefree]

I'm still building, but would skip the fabric on the next one. I might still glass tape the corners, but no cloth on walls and roof. It's too much work for too little gain. Also, my tear, a 5x10, 5 feet high, has used 3-1/2 gallons epoxy and I'm not done yet. That's 3 coats, sanded smooth.

[doug hodder]

I like the way hardboard rounds curves but I am unsure if it will make a good base for the epoxy or not. Your thoughts?

Just my opinion...I'd do 1/4" ply or 2 layers of 1/8" on a tight curve, epoxy or not, it'll take a hit from something a lot better than hardboard. Others opinions may vary. Doug

[Esteban]

I'm fiberglassing my teardrop with epoxy and fiberglass cloth purchased from Raka.com. The TD is about 5' wide by 11' long. A 3 gallon epoxy kit should be more than enough to do the sides, top and galley hatch.

Provided you don't make too many boo boos.

I recently stripped off all the fiberglass from one side because the base layer hadn't set up hard. I found this out when I accidentally sanded through the fiberglass cloth to begin smoothing and fairing the wall. My sander gummed up. The top layers were hard, but the base layer of epoxy was gummy. After 8 months.

Mildly A frustrating day ensued as I used a heat gun, a scraper and a sander to removed all the fiberglass down to bare wood.

The reason for my boo boo AFAIK was because I may have mixed in too much hardener (not good to do...it doesn't make it even harder), or not mixed the epoxy well, or long, enough.

I'm now almost done redoing the wall. The first time I did the walls I used 3.2 ox. tight weave fiberglass cloth. As a fiberglassing newbie I was concerned about weight so I used a lightweight cloth. When I stripped it all off with the heat gun it was almost paper thin. 4 or 6 oz. plain weave cloth would have been fine and would still be much lighter than aluminum.

I redid the wall using 4 oz. plain weave cloth I had on hand for later doing the roof. The looser weave of plain weave cloth makes it much easier to squeegee out air bubbles. This time I used Raka's fast hardener because our high temps recently have been in the 50s to low 70s. So far so good with the redo. The new fiberglass has set up hard. It sands out dusty, not gooey.

I'm beginning to fair (smooth) out the walls with a mixture of epoxy and micro balloons. As I sanded, sanded, and sanded some more I started thinking of the Karate Kid. "Wax on, wax off" rolled around in my head.

My walls are being built flat on a bench. If the fairing goes well they will be ready to attach to the floor within a couple of weeks.

Because of my boo boo I ordered another 3 gallon kit. I'll use the "extra" epoxy for sealing inside the sandwich walls and to attach the inner cabin wall 1/8" plywood to the sandwich frame.

In my opinion fiberglassing your plywood walls is optional. Mine are pieced together (3 pieces of plywood per wall) and the fiberglass cloth helped strengthen and smooth out the joints. If you build a wall from one piece of plywood you could easily skip using fiberglass cloth.

[bbarry]

I didn't use 1 full gallon of material in my construction or top coating on any 1 tear. Doug

Because of my boo boo I ordered another 3 gallon kit.

Why the large difference in how much epoxy folks use? I know that Esteban used glass, while Doug doesn't, but I'm guessing us newbies use entirely too much? It took me 25 oz. just to skin (bond) one side of my frame. I'm thinking that I slopped on way too much. On the other hand, I don't want a dry bond. Any rules of thumb for gluing and/or coating?

Brad

[doug hodder]

I dunno....I have never figured that out on the 3 gallon kit thing. It always seemed like a lot to me, but I've only used West System so don't know about the Raka epoxies. Cloth will however suck up more resin. I'd like to play with both systems side by side sometime to really see what the difference is, but in the meantime I just use what works for me.

If you are using it as a construction adhesive mix in some colloidal silica. It'll thicken it up like peanut butter if you want. Some people use wood flour. At any rate, by doing this, it won't run and will fill the joint with glue. As you spend more time working with epoxy, you'll find out all sorts of tricks to conserve and utilize it. Doug

[Juneaudave]

I believe Doug uses a mini roller with a yellow West System epoxy foam roller cut in half to coat the wood. That applies a relatively thin and even coat.

I typically use a brush, and when glassing, put the first coat on thick (the wet out) and squeegee off the excess...then aaply a "fill coat" to fill the weave, and a third and/or fourth coat to build a sanding surface (you don't want to sand into your glass).

Others you a squegee, with or without glass to apply.

So...there is a big, big difference. It all depends on what you are looking to do...

Make sense?

[doug hodder]

Good point Dave....Yup...I do use a roller to apply, I think the thinner coats are easier to sand out than a couple of heavier ones to get the surfaces nice and flat, but if doing cloth, you don't want to starve the weave of resin so gotta lay it on heavier. If you work it right, you can do both sides on a tear using the same 1/2 a roller without it setting up on you. Doug

[bfitz]

If I were to glass a trailer, I'd only glass the top for protection from hail or rocks thrown from my vehicle. I would also use epoxy to seal the wood on the sides.

As for how much epoxy you'll need, I have no idea how much is necessary for a trailer. I've done a kayak that I can base few observations on.

1) Don't put it on too thick to start with. You want enough to penetrate the glass, but not so much that it will drip. Put too much on, and you'll spend your life sanding. I applied the epoxy by pouring and spreading with plastic spatulas (margarine tops, cut to profile). Use a light touch to avoid dragging the glass from its position.
2) For subsequent coats, you will need VERY LITTLE epoxy. The secondary coats are only used to fill low points in the finish. When making the yak, I used roughly 1/2 cup to cover 1 to 2 sq feet in the first coat (guessing here). The second and third coats, 1/2 cup could do the entire hull. By using a spatula, low points were filled and only minimal extra was applied. Have extra spatulas, as the epoxy will harden on them as you work.
3) I came across a great hint for measuring/mixing. Use clear plastic containers. Put one cup inside another and measure out an appropriate amount of resin (use water the first time) into the inner cup. Mark the height of the resin on the outer cup. Then measure an appropriate amount of hardener into the inner cup. Again, mark the outer cup. Then, when measuring, put a clean cup in the outer (gauge) cup, and you can pour in the resin and hardener instead of counting 50 pumps. This'll save you a lot of time.

The only other thing I can say (and it should be said over and over) is that sanding hardened epoxy s***s. Don't put it on too thick...you'll dread working on your tt.

When you're done, I'd consider putting some marine varnish with UV blockers on the whole thing.